A variety of implantable medical devices (IMDs) for delivering a therapy, monitoring a physiological condition of a patient or a combination thereof have been clinically implanted or proposed for clinical implantation in patients. Some IMDs may employ one or more elongated electrical leads carrying stimulation electrodes, sense electrodes, and/or other sensors. IMDs may deliver therapy to and/or monitor conditions of a variety of organs, nerves, muscle or tissue, such as the heart, brain, stomach, spinal cord, pelvic floor, or the like.
In order to promote patient comfort, IMDs are often miniaturized. In some cases, IMDs are miniaturized in order to be implantable at a desired anatomical site or enable minimally invasive implant procedures to be used. Available space within an IMD housing for a power supply that powers IMD electronic circuitry is therefore limited. Depending on the particular medical application, an IMD may be required to function for weeks, months or even years, sometimes continuously. The power supply can become depleted requiring IMD replacement.